lhcf: physics results on forward particle production at lhc

+

LHCf: physics results on forward particle production at

LHC

Oscar AdrianiUniversity of Florence & INFN Firenze

EDS Blois 2013Saariselka, September 9th, 2013

O. Adriani LHCf physics results on forward particle production at LHC Saariselka, September 9th, 2013

+Physics MotivationsImpact on HECR Physics


+

PROTON

IRON

Auger Coll. ICRC2011

10191018

Xmax distribution

Extensive air shower observation • longitudinal distribution • lateral distribution • Arrival direction

Astrophysical parameters • Spectrum• Composition• Source distribution

Air shower development

HECRs

Xmax is the depth of air shower maximum inthe atmosphere. An indicator of CR composition.

Uncertainty of hadron interaction models

Uncertainty in the interpretation of <Xmax>

High Energy Cosmic Rays


+

④ secondary interactionsnucleon, p

① Inelastic cross section If large s: rapid developmentIf small s: deep penetrating

② Forward energy spectrum

If softer shallow developmentIf harder deep penetrating

If large k (p0s carry more energy) rapid developmentIf small k (baryons carry more energy) deep penetrating

How accelerator experiments can contribute?

③ Inelasticity k=1-Elead/Eavail


+ Models tuning after the first LHC data

PROTON

IRON

Auger Coll. ICRC2011

10191018

Xmax as function of E and particle type

T.Pierog,Cosmic QCD 2013 conference in Paris

Pre LHC Post LHC


+LHCf @ LHCThe experimental set-up


+ The Large Hadron Collider (LHC)pp 450GeV+450GeV Elab ~ 2x1014eV

pp 　 3.5TeV+3.5TeV Elab ~ 2.6x1016eVpp 6.5TeV+6.5TeV Elab ~1017eV

ATLAS/LHCfLHCb/MoEDAL

CMS/TOTEM

ALICE

Total cross section ↔ TOTEM, ATLAS, CMS Multiplicity ↔ Central detectors Inelasticity/Secondary spectra ↔ Forward

calorimeters (LHCf, ZDCs)

R. Orava, (2007)

Full rapidity coverage!

+


O.Adriania,b, L.Bonechib, M.Bongia, G.Castellinic,b, R.D’Alessandroa,b, M.Haguenauere, Y.Itowf,g, K.Kasaharah, K. Kawadeg, Y.Makinog,

K.Masudag, Y.Matsubarag, E.Matsubayashig, H.Menjoi, G.Mitsukag, Y.Murakig, P.Papinib, A.-L.Perrotj, D.Pfeifferj, S.Ricciarinic,b,

T.Sakog, Y.Shimitsuh, Y.Sugiurag, T.Suzukih, T.Tamurak, S.Toriih, A.Tricomil,m, W.C.Turnern, K.Yoshidao, Q.Zhoug

a) University of Florence, Italyb) INFN Section of Florence, Italy c) IFAC-CNR, Florence, Italyd) IFIC, Centro Mixto CSIC-UVEG, Spaine) Ecole Polytechnique, Palaiseau, Francef) KMI, Nagoya University, Nagoya, Japang) STELAB, Nagoya University, Japanh) RISE, Waseda University, Japani) School of Science, Nagoya University, Japanj) CERN, Switzerlandk) Kanagawa University, Japanl) University of Catania, Italym) INFN Section of Catania, Italyn) LBNL, Berkeley, California, USAo) Shibaura Institute of Technology, Japan

The LHCf Collaboration

+


LHCf: location and detector layout

44X0, 1.6 lint

INTERACTION POINT

IP1 (ATLAS)

Detector IITungsten

ScintillatorSilicon

mstrips

Detector ITungsten

ScintillatorScintillating

fibers140 m 140 m

n π0

γ

γ8 cm 6 cm

Front Counter Front Counter

Arm#1 Detector20mmx20mm+40mmx40mm4 X-Y SciFi tracking layers

Arm#2 Detector25mmx25mm+32mmx32mm4 X-Y Silicon strip tracking layers

Energy resolution: < 5% for photons 30% for neutronsPosition resolution: < 200μm (Arm#1) 40μm (Arm#2)Pseudo-rapidity range:η > 8.7 @ zero Xing angleη > 8.4 @ 140urad

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Determination of energy from total energy release

PID from shapeDetermination of the impact point

Measurement of the opening angle of gamma pairs

Identification of multiple hit

25mm Tower 32mm Tower600GeV 　　 photon

420GeV 　　 photon

Longitudinal development measured by scintillator layers

Transverse profile measured by silicon –strip layers

`

X-view

Y-view

`

Reconstruction of 0 mass:

A very clear p0 in Arm2

+


Year Beams

Beam energy

Proton equivalent

energy in the LAB (eV)

Setup

2009 p - p 450+450 GeV 4.3 1014 Arm1+Arm

22009/20

10 p - p 3.5+3.5 TeV 2.6 1016 Arm1+Arm

2

2013 p – Pb 4 TeVproton 1.3 1016 Arm2

2013 p - p 1.38+1.38 TeV 4.1 1016 Arm2

2015 p - p 6.5+6.5 TeV 9 1016 Arm1+Arm

2 upgraded

?p –

light ions

? ? ?

LHCf Physics Program


+Inclusive photon spectrum analysis at 7 TeV and 900 GeV“Measurement of zero degree single photon energy spectra for √s = 7 TeV proton-proton collisions at LHC“PLB 703 (2011) 128“Measurement of zero degree single photon energy spectra for √s = 900 GeV proton-proton collisions at LHC“PLB 715 (2012) 298

A short review of already published results

Forward p0 spectra at 7 TeV“Measurement of forward neutral pion transverse momentum spectra for √s = 7TeV proton-proton collisions at LHC“PRD 86 (2012) 092001

+


DATA vs MC : comp. 900GeV/7TeV90

0GeV

7TeV

η>10.94 8.81<η<8.9

• None of the model nicely agrees with the LHCF data• Here we plot the ratio MC/Data for the various models• > Factor 2 difference

+


DATA : 900GeV vs 7TeV

Preliminary

Data 2010 at √s=900GeV(Normalized by the number of entries in XF > 0.1)Data 2010 at √s=7TeV (η>10.94)

900GeV vs. 7TeVwith the same PT region

Normalized by the number of entries in XF > 0.1 No systematic error is considered in both collision

energies.

XF spectra : 900GeV data vs. 7TeV data

small-η

Coverage of 900GeV and 7TeV results in Feynman-X and PT

Good agreement of XF spectrum shape between 900 GeV and 7 TeV.weak dependence of <pT> on ECMS

+


p0 PT spectra for various y bin: MC/dataEPOS gives the best agreement both for shape and yield.

DPMJET 3.04 QGSJETII-03 SIBYLL 2.1 EPOS 1.99 PYTHIA 8.145

0 0.6PT[GeV]

0 0.6PT[GeV] 0 0.6PT[GeV] 0 0.6PT[GeV]

0 0.6PT[GeV] 0 0.6PT[GeV]

MC/

Data

MC/

Data


+ p0 analysis at √s=7TeV

1. Thermodynamics (Hagedron, Riv. Nuovo Cim. 6:10, 1 (1983))

2. Numerical integration actually up to the upper bound of histogram

• Systematic uncertainty of LHCf data is 5%.• Compared with the UA7 data (√s=630GeV)

and MC simulations (QGSJET, SIBYLL, EPOS).• Two experimental data mostly appear to lie

along a common curve→ no evident dependence of <pT> on ECMS.

• Smallest dependence on ECMS is found in EPOS and it is consistent with LHCf and UA7.

• Large ECMS dependence is found in SIBYLL

PLB 242 531 (1990)

ylab = ybeam - y

Submitted to PRD (arXiv:1205.4578).

pT spectra vs best-fit function Average pT vs ylab

YBeam=6.5 for SPSYBeam=8.92 for7 TeV LHC


+On going analysisNeutrons at 7 TeV pp collisionsThe 2013 p-Pb run


+ Very big discrepancies

between models Useful measurement!

Performance for neutrons 35% Eres 1mm Position Res.

@ 1.5TeV nAnd….Detector performanceis also interaction model dependent.

Unfolding is essential to extract physics results from the measured spectra

The challenge of n analysisMC

Detector performance

+


L90%L20%

Layer[r.l.]

hadronphoton

projection along the sloped

line

L 90%

L20%

Shower development in the small

calorimeter tower

Neutron identification

• Particle Identification with high efficiency and small contamination is necessary

• A 2D method based on longitudinal shower development is used

• L20%(L90%): depth in X0 where 20% (90%) of the deposited energy is contained

• L2D=L90%-0.25 L20%

• Mean purity in the 0-10 TeV range: 95%

• Mean efficiency: ~90%L2D

+


`

Small tower7 TeV pp

Large tower7 TeV pp

Preliminary n spectrum

Unfolding is in progress…..No efficiency correctionNo rapidity selectionNo unfoldingNo systematic errors


+

3.5cm,4.0cm

The 2013 p-Pb run at sNN = 5 TeV

2013 Jan-Feb for p-Pb/Pb-p collisions• Installation of the only Arm2 at one

side (silicon tracker good for multiplicity)

• Data both at p-side (20Jan-1Feb) and Pb-side (1fill, 4Feb), thanks to the swap of the beams

Details of beams and DAQ– L = 1x1029 – 0.5x1029cm-2s-1

– ~200.106 events– b* = 0.8 m, 290 mrad crossig angle– 338p+338Pb bunches (min.DT = 200 ns), 296 colliding at IP1– 10-20 kHz trig rate downscaled to approximately 700 Hz– 20-40 Hz ATLAS common trig. Coincidence successful! – p-p collisions at 2.76 TeV have also been taken

p Pb

IP8IP2IP1

Arm2

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Physics in pA

Nuclear effect in the forward particle productionPhoton spectra for different impact parameters

Photon spectra at different η in p-p, p-N and p-Pb collisionsIs p-Pb good test for p-atmosphere?

p-p p-N p-Pb

QGSJET II-04All η8.81<η<8.99η>10.94

(Courtesy of S.Ostapchenko)

Please observe that the impact parameter can be obtained from Atlas Lucid, for ex.!

+


Impact points and beam center2d distribution of impact point: neutrons are more peaked

DATA

DATA

Determination of the beam center (BC)

2d gaussian fit𝑥𝐵=(1.07±0.09 )mm

𝑦𝐵=(−1.87 ±0.08 )mm

Coordinates of the beam center with respect to the expected beam center

n

n

2013p-Pb run

p-remnant side

DATA

+


Photon - y

Neutron - x

Neutron - y

Photon - x

PRELIMINARY PRELIMINARY

PRELIMINARY PRELIMINARY

Neutrons are well peaked at the beam center

Forward baryon production is important to understand the muon excess [T. Pierog, K. Werner PRL 101 171101(2008)]

and n impact point distributions (p-remnant)

+


PRELIMINAR

Y

PRELIMINARY25 mm

32 mm

Detailed simulations with the available hadronic interaction models are on-going for a comparison with data• Transportation of secondary particles

from IP to detector, beam pipe structure, magnetic fields along the path and detector’s response will be taken into account

Vertical bars: statistical errors

p-Pb run: spectra

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PRELIMINARY

PRELIMINAR

Y

p-Pb run: p0

+


p-p at 13TeV (2015)Main target: measurement at the LHC design energy.Study of energy scaling by comparison with √s = 900 GeV and 7 TeV data Upgrade of the detectors for radiation hardness.

p-light ions (O, N) at the LHC (2019?)It allows studying HECR collisions with atmospheric nuclei.

RHICf experiment at RHICLower collision energy, ion collisions.LOI to the RHIC committee submitted

p-p collisions:• Max. √s = 500 GeV• Polarized beams Ion collisions:• Au-Au, d-Au • Max. √s = 200 GeV• Possible, d-O,N (p-

O,N) Cosmic ray – Air @ knee energy.

10cm

detector

LHCf: future plan

+ Physics of RHICf

Energy Scaling of Very Forward at p-p √s=500GeV Measurement at p-light ion collisions (p-O) √sNN=200GeV Asymmetry of Forward Neutron with polarized beams

LOI submitted to the RHIC committee and nicely appreciated More news soon

Physics of RHICf

Y. Fukao et al.,PLB 650 (2007)

The STAR Collaboration, PRL 97 (2006) 152302

Nuclear modification factor at d-Au 200GeV



+ Conclusions LHCf is a small experiment at LHC dedicated to forward physics

Important for Very High Energy Cosmic-Ray (VHECR) Physics

We have published spectra of photons and neutral pions for pp interactions at s = 900 GeV and s = 5 TeV None of the hadronic interaction models that we have considered can reproduce the data within

the errors, but data lie anyway between the models On-going data analysis for the hadronic component (neutrons)

p-Pb run at the beginning of 2013 Successful data taking in p-remnant and Pb remnant side Common operations with ATLAS (trigger exchange) On-going data analysis (some hints for interesting results!!!)

Future plan Continue and finalize the on-going data analysis (start also ATLAS/LHCf common analysis) Complete the upgrade of the detectors for radiation hardness Data taking for pp collisions at s = 13 TeV (2015) Run p-light ions at LHC (2019?) Operations at RHIC (p-O or p-N at lower energies)


+Backups

+Muon excess at Pierre Auger Obs.

Pierre Auger Collaboration, ICRC 2011 (arXiv:1107.4804)

Pierog and Werner, PRL 101 (2008) 171101

Auger hybrid analysis• event-by-event MC selection to fit

FD data (top-left)• comparison with SD data vs MC

(top-right)• muon excess in data even for Fe

primary MCEPOS predicts more muon due to larger baryon production => importance of baryon measurement


+

xF = E/E0

Playing a game with air shower (effect of forward meson spectra)

E=E1+E2

E1E

2

xF = E/E0

pT

• DPMJET3 always over-predicts production• Filtering DPMJET3 mesons

• according to an empirical probability function, divide mesons into two with keeping pT

• Fraction of mesons escape out of LHCf acceptance

• This process• Holds cross section• Holds elasticity/inelasticity• Holds energy conservation• Changes multiplicity• Does not conserve charge event-by-event



+ An example of filtering

π0 spectrum

photon spectrum

DPMJET3+filter

2.5x1016 eV proton~30g/cm2

Vertical Depth (g/cm2)

AUGER, ICRC 2011

EPS-HEP 2013 July 18-24


+η

∞

8.5

What LHCf can measure

Energy spectra and Transverse momentum distribution of

Multiplicity@14TeV Energy Flux @14TeV

Low multiplicity !! High energy flux !!

simulated by DPMJET3

• Gamma-rays (E>100GeV,dE/E<5%)• Neutral Hadrons (E>a few 100 GeV, dE/E~30%)• π0 (E>600GeV, dE/E<3%)

at pseudo-rapidity range >8.4

Front view of calorimeters @ 100μrad crossing angle

beam pipe shadow

+


Comparison wrt MC Models at 7 TeVDPMJET 3.04 SIBYLL 2.1 EPOS 1.99 PYTHIA 8.145 QGSJET II-03

Gray hatch : Systematic Errors

Magenta hatch: MC Statistical errors

+


Comparison wrt MC Models at 900 GeV


+ h Mass Arm2 detector, all runs with zero crossing angleTrue h Mass: 547.9 MeVMC Reconstructed h Mass peak: 548.5 ± 1.0 MeVData Reconstructed h Mass peak: 562.2 ± 1.8 MeV (2.6% shift)


+Type-I Type-II

Type-II at small tower

Type-II at large tower

Type-ILHCf-Arm1

Type-IILHCf-Arm1

LHCf-Arm1Data 2010

BG

Signal

Preliminary

•Large angle•Simple•Clean•High-stat.

•Small angle•large BG•Low-stat., but can cover•High-E•Large-PT

π0 analysis at √s=7TeVSubmitted to PRD (arXiv:1205.4578).

+


p0 Data vs MC

+


p0 Data vs MC dpmjet 3.04 & pythia 8.145

show overall agreement with LHCf data for 9.2<y<9.6 and pT <0.25 GeV/c, while the expected p0 production rates by both models exceed the LHCf data as pT becomes large

sibyll 2.1 predicts harder pion spectra than data, but the expected p0 yield is generally small

qgsjet II-03 predicts p0 spectra softer than LHCf data

epos 1.99 shows the best overall agreement with the LHCf data.

behaves softer in the low pT region, pT < 0.4GeV/c in 9.0<y<9.4 and pT <0.3GeV/c in 9.4<y<9.6

behaves harder in the large pT region.

+MC study of n response


E vs. <Evis> at centerPosition resolution

Correction for position dependent shower leakage

Energy resolution (uniform incident on calorimeters)

+


Proton remnant side – Photon spectra

+


Proton remnant side - Neutron spectra


+ Proton-remnant side – p0

We can detect p0!

Important tool for energy scale

And also for models check…..

+Lead-remnant side – multiplicityPlease remind that EPOS does not consider Fermi motion and Nuclear Fragmentation

n

Small tower Big tower


+


Common trigger with ATLAS

LHCf forced to trigger ATLAS Impact parameter may be determined by ATLAS Identification of forward-only events

MCimpact parameter vs. # of particles in ATLAS LUCID

lhcf: physics results on forward particle production at lhc

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